1. Field of the Invention
The present invention relates to an endoscope for a widespread use for various purposes.
2. Description of the Related Art
In a conventional endoscope, a light source is usually a peripheral device to be connected to an endoscope. Namely, a light source is provided separately from an endoscope. In recent years, an endoscope is combined with a peripheral device, and an LED is built into an endoscope for saving power and simplifying the structure (reducing the size) of the whole endoscope apparatus. In this case, the LED is provided at a distal end portion of an insertion portion of the endoscope, and directly illuminates an object area, or the LED is built into an operation portion, and its light is guided to a distal end portion of an insertion portion through a light guide fiber. In the former case, the distal end portion of the insertion portion needs to be made relatively large owing to dimensional restrictions, or to effectively diffuse heat generated from the LED.
However, in a medical endoscope, a distal end portion of an insertion portion needs to be as small as possible in order to minimize the discomfort experienced by the patient. In this case, an LED is built into an operation portion (as in the later case). In this case, an outer casing of the operation portion of the endoscope is constructed to be watertight, and resistant to chemicals by using engineering plastics. This also reduces the weight. Thus, the LED is built into the operation portion enclosed with plastic with low thermal conductivity, which makes it difficult to radiate heat generated by the LED to the outside.
When a surface temperature of the operation portion held by an operator is increased by the light emitted from the LED, this is unpleasant for the operator. Therefore, it is preferable to prevent conduction of heat from the LED to a grip part of the operation portion. On the other hand, it is necessary to radiate heat emitted from the LED to prevent a decrease in the light-emitting efficiency of the LED, and to prevent a reduction of the life of the LED.
Jpn. Pat. Appln. KOKAI Publication No. H9-122065 discloses a structure to effectively radiate heat generated by a light-emitting element provided in an operation portion to the outside, by transmitting heat to a heat radiation part exposed to the outside surface of an operation portion by using a heat pump.